Mass/Time  IV mL Rate Questions
Give an order in quantity of mass per time, determine the necessary IV flow rate
in mL/hr based on the given mass per volume. These types of problems are often
used in critical care nursing.
Formula:
Example: Give patient
500 mg of dopamine in
250 mL of D5W to infuse at
20 mg/hr. Calculate the flow rate in mL/hr.

x Volume (mL)

= Y (Flow Rate in mL/hr)

Example: Aggrastat at
12.5 mg in
250 mL is prescribed to be infused at
a rate of
6 mcg/kg/hr in a patient who
weighs 100 kg. At what flow rate in mL/hr will you set the pump?

x Volume (mL)

= Y (Flow Rate in mL/hr)


The first step is to convert the order per time to the amount required for this
particular patient. This is a Dosage By Weight Question.
100 kg is the weight in kg and
6 mcg/kg/hr is a dosage in terms of kg.
Weight in Kg * Dosage Per Kg

= Y (Required Dosage)

100 kg * 6 mcg/kg/hr

= 600 mcg/hr

Convert 600 mcg/hr to mg/hr.
 mcg → mg → g → kg ( ÷ by 1,000 )
 600 ÷ 1,000 = 0.6 mg/hr
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